Single-crystal substrates, notably made of semiconductor materials such as silicon, are commonly used in the field of microelectronics. Such substrates are typically obtained starting from ingots. More precisely, the fabrication of these substrates comprises:                the growth of an ingot starting from a seed of the crystal, for example, by the Czochralski method, the orientation of the seed determining the crystal orientation of the ingot,        the slicing of the ingot into a plurality of sections, the slicing being carried out along planes substantially perpendicular to the axis of the ingot,        the formation of a notch on the circumference of each section, the notch extending in the axial direction of the section,        the slicing of each section into a plurality of wafers, the slicing being carried out along planes substantially perpendicular to the axis of the section,        the implementation of a treatment for finishing the wafers, which may notably comprise polishing, cleaning, and/or the formation of peripheral chamfers, in order to form a respective substrate.        
An application of such a single-crystal substrate is the transfer of a layer from this substrate, then called a “donor substrate,” onto another substrate called a “receiver substrate.” A known technique for such a transfer is the SMART CUT® method, in which, by implantation into the donor substrate, a weakness region is created that bounds a layer to be transferred, the donor substrate is bonded onto the receiver substrate and the substrate is detached along the weakness region, in such a manner as to transfer the layer onto the receiver substrate.
Following this transfer, the free surface of the transferred layer, which is opposite the surface of the donor substrate that has been bonded to the receiver substrate, exhibits a high roughness, which requires finishing processing steps.
Indeed, this roughness has a strong influence on the performance characteristics of the electronic devices formed in or on the transferred layer. For example, a high roughness leads to a significant variability in the threshold voltages of the transistors fabricated in or on this layer.
In order to repair the surface, known solutions are to apply various finishing processes, notably a thermal annealing, aimed at smoothing the surface.
However, the roughness of the transferred layer is not optimal and needs to be reduced in order to improve the performance characteristics of the devices intended to be fabricated in or on the transferred layer.